I started my 3D printer upgrade series with the Quick tool change which is still one of my coolest upgrades. However, it missed something because if you change to a different tool, you always have to place the hot end somewhere. With the swappable hot end it is possible to disconnect the whole hot end like the Ultimaker printers. Another advantage of this, besides being able to disconnect your hot end, is that you can use different hot ends for different materials or nozzle diameters. After I came up with this idea I found a couple of similar approaches but nothing with which the bowden tube itself could be disconnected.
Another cool thing: if you use a laser engraver, you don’t have to add an extra wire or switches to your control board and you can just connect it directly.